Question

I’m a novice javascript programmer and I always have trouble with the setInterval. W3Schools makes it look so easy but I can never get it to work when i need to. Here I have a span I want to make ‘flash’.

var id = window.setInterval(function(){
             if($("#span1").css("color") == "red"){
                 $("#span1").css("color","blue");
             }
             else{
                 $("#span1").css("color","red");}
         }, 100);

I keep getting a SYNTAX ERROR: Unexpected token ILLEGAL. What am I doing wrong here?

NOTE: I know there’s some jQuery method that could handle this easily. I’m trying to gain a better understanding of this JS function.

UPDATE I fixed the syntax error. (Missing quotation). Now I get an error undefined.

Answer 1

You probably copy and pasted the code and it has some bad characters in it. Try re-typing the code manually in a new file.

Side-note, you can make the whole thing a hell of a lot more efficient and reliable:

(function() {
    var thespan = document.getElementById('span'),
        toggle = true;
    window.setInterval(function() {
        toggle = !toggle;
        thespan.style.color = toggle ? "red" : "blue";
    },100);
})();